Specialist trainee ophthalmologist Rupal Morjaria said at first a mass of 17 contact lenses were found, before another 10 were discovered on further examination.

"None of us have ever seen this before," she told specialist magazine Optometry Today.

"It was such a large mass. All the 17 contact lenses were stuck together. We were really surprised that the patient didn't notice it because it would cause quite a lot of irritation while it was sitting there."

The patient, who has not been named, had her cataract surgery postponed following the discovery.

"Because she had harboured these contact lenses in her eye for an unknown length of time, if we had operated she would have had a lot of bacteria around her conjunctiva," Morjaria said.

"She was quite shocked. When she was seen two weeks after I removed the lenses she said her eyes felt a lot more comfortable. She thought her previous discomfort was just part of old age and dry eye."

Morjaria said she decided to make the case public to raise awareness of the importance of regular check-ups with optometrists.

"In this day and age, when it is so easy to purchase contact lenses online, people become lax about having regular check ups," she added.

"Contact lenses are used all the time, but if they are not appropriately monitored we see people with serious eye infections that can cause them to lose their sight."